Technical Field
[0001] The present invention relates to a ball for ball games and a method for manufacturing
the ball for ball games.
Background Art
[0002] There has conventionally been known a ball for ball games that has a ball body and
an outer layer that is configured by stitching adjacent leather panels together and
covers the ball body. This type of ball for ball games is disclosed in, for example,
Patent Literature 1 and 2.
[0003] The ball for ball games disclosed in Patent Literature 1 has a ball body 57 consisting
of a bladder 52 and a reinforcing layer 53, and an outer layer 55 disposed on the
outside of the ball body 57, as shown in Fig. 14. The outer layer 55 has a plurality
of leather panels 54. The leather panels 54 each have a leather 54c and a foam material
54d bonded to the rear surface of the leather 54c. A peripheral portion of each leather
panel 54 has a folding portion 59, wherein the adjacent leather panels 54, 54 are
stitched together with a stitching thread 63 at the folding portion 59.
[0004] In this ball for ball games, the foam material 54d is bonded to the rear surface
of the leather 54c, and an outer end portion of the leather panel 54 is thinner than
the center of the leather panel 54. Therefore, the peripheral portion of the leather
panel 54 is not bulging, and the ball feels soft. Moreover, the leather panels 54
are bonded to each other, preventing water from seeping into the leather panels 54
from between the leather panels 54, 54.
[0005] However, stitching the foam materials 54d together at the folding portions 59 of
the leather panels 54 generates weak sewing strength. As a result, seam tear and stitch-skipping
are likely to occur at the time of sewing. In addition, because the strength of the
foam materials 54d is extremely lower than that of the stitching thread 63, the foam
material 54d and the leather 54c tear at the stitched portion when the ball is subjected
to impact when kicked, resulting in a critical problem that the leather panels 54
come off.
[0006] In the ball for ball games disclosed as an embodiment in Patent Literature 2 as well,
the peripheral portion of each leather panel 54 is not bulging due to the presence
of a pad material 65 as shown in Fig. 15, and the ball feels soft. However, because
the adjacent leather panels 54, 54 are not bonded to each other, the force that splits
the adjacent panels 54, 54 apart acts on the stitched portion between the leather
panels 54 when the ball for ball games is in use, possibly exposing the stitching
thread 63. In addition, sewing strength is weak because the leathers 54c are stitched
together. Consequently, seam tear and stitch-skipping are likely to occur. There is
also a risk that this action of the force splitting the adjacent leather panels 54,
54 apart might tear the stitching thread 63. Furthermore, water is absorbed between
the leather panels 54, 54.
[0007] The ball for ball games disclosed as an embodiment in Patent Literature 2 has a lining
layer 67, as shown in Fig. 16. This lining layer 67 is stitched together with the
leather 54c and an intermediate layer 69, providing high sewing strength. In this
embodiment, however, the adjacent leather panels 54, 54 are not bonded to each other,
and due to the absence of the pad material 65, the peripheral portion of each leather
panel 54 bulges. As a result, when this ball for ball games is in use, the force that
splits the adjacent panels 54, 54 apart acts more easily on the stitched portion of
each leather panel 54, compared to the embodiment shown in Fig. 15. Consequently,
the stitching thread 63 becomes exposed easily. In addition, there is a risk that
this action of the force splitting the adjacent leather panels 54, 54 apart might
tear the stitching thread 63.
Citation List
Patent Literature
Summary of Invention
[0009] An object of the present invention is to provide a ball for ball games and a method
for manufacturing a ball for ball games, which can solve the foregoing problems.
[0010] A ball for ball games according to one aspect of the present invention has a ball
body and a spherical shell-shaped outer layer having a plurality of leather panels
and disposed on the outside of the ball body. The plurality of leather panels each
have a main body and an extending portion that is thinner than the main body and extends
from a front-side portion of an outer end surface of the main body to configure an
outer end surface of the leather panel. The extending portions of adjacent leather
panels are bonded to each other with an adhesive and stitched together with a stitching
thread. The extending portion is provided with a reinforcing member for reinforcing
an area thereof stitched with the stitching thread.
[0011] A method for manufacturing a ball for ball games according to one aspect of the present
invention is a method for manufacturing a ball for ball games that has a ball body
and a spherical shell-shaped outer layer having a plurality of leather panels and
disposed on the outside of the ball body, the method having: a leather panel formation
step of obtaining each of the leather panels by forming, in a member for leather panel,
a main body and an extending portion reinforced with a reinforcing member; an application
step of applying an adhesive to an outer surface of each of the extending portions;
a joining step of joining the outer surfaces of the extending portions of two leather
panels to which the adhesive is applied; a stitching step of stitching together, with
a stitching thread, the extending portions of the leather panels, the outer surfaces
of which have been joined to each other; and an insertion step of inserting the ball
body into a spherical shell body that is obtained by repeating the joining step and
the stitching step, to obtain a ball.
Brief Description of Drawings
[0012]
[Fig. 1] Fig. 1A is a diagram showing the appearance of a ball for ball games according
to an embodiment of the present invention.
[Fig. 2] Fig. 2 is a cross-sectional diagram taken along line II-II of Fig. 1.
[Fig. 3] Fig. 3 is a diagram equivalent to Fig. 2, according to another embodiment
of the present invention.
[Fig. 4] Fig. 4 is a diagram equivalent to Fig. 2, according to yet another embodiment
of the present invention.
[Fig. 5] Fig. 5 is a diagram for explaining a pasting step.
[Fig. 6] Fig. 6 is a diagram for explaining a cutting step.
[Fig. 7] Fig. 7 is a diagram for explaining an extending portion formation step.
[Fig. 8] Fig. 8 is a diagram showing a leather panel after an extending portion is
formed.
[Fig. 9] Fig. 9 is a diagram for explaining an application step.
[Fig. 10] Fig. 10 is a diagram for explaining a joining step.
[Fig. 11] Fig. 11 is an external view of a spherical shell body.
[Fig. 12] Fig. 12 is a diagram showing a stitched portion between two leather panels
of the spherical shell body.
[Fig. 13] Fig. 13 is a diagram for explaining a solidification step.
[Fig. 14] Fig. 14 is a diagram showing a conventional ball for ball games.
[Fig. 15] Fig. 15 is a diagram showing a conventional ball for ball games.
[Fig. 16] Fig. 16 is a diagram showing a conventional ball for ball games.
Description of Embodiments
[0013] Embodiments for implementing the present invention are described hereinafter in detail
with reference to the drawings.
[0014] Fig. 1 shows the appearance of a soccer ball as an embodiment of a ball for ball
games according to the present invention. This soccer ball has an outer layer 5 having
a plurality of leather panels 4, 4... Pentagonal panels (twelve) and hexagonal panels
(twenty) are used as the leather panels 4, 4... Only twelve pentagonal panels may
be used to configure the leather panels 4, 4... The spherical surface may be covered
with the plurality of panels 4, 4... of a different shape. One of the leather panels
4 is provided with a hole 1 for a valve that is used for putting air into the soccer
ball.
[0015] The soccer ball has a ball body 7 disposed on the inside of the outer layer 5, as
shown in Fig. 2. Specifically, the soccer ball has the ball body 7 and the outer layer
5 disposed on the outside of the ball body 7. The ball body 7 has a hollow-shaped
bladder 2 and a reinforcing layer 3 provided on the outside of the bladder 2. The
bladder 2 is configured into a hollow by an air-impervious rubber such as a butyl
rubber or a latex rubber. Compressed air is introduced into the bladder 2.
[0016] The reinforcing layer 3 is a layer provided for the purpose of realizing stable quality
of a ball, and is formed by winding several thousand meters of a fiber, such as nylon
filament, in various directions. The presence of the reinforcing layer 3 can improve
the degree of sphericity, durability, outer diameter, form maintainability, and the
like.
[0017] Note that the reinforcing layer 3 is not limited to the foregoing configuration.
For example, the reinforcing layer 3 may be configured by pasting woven fabrics such
as a cotton fabric. The reinforcing layer 3 may also be formed by stitching a plurality
of woven fabrics into a spherical shape. The reinforcing layer 3 can be omitted in
case of creating, for example, a ball for an infant. The body 7 can be configured
with an elastomer material capable of providing the reinforcement effect and the bladder
effect (air retention function + rebound function).
[0018] The outer layer 5 is disposed on the outside of the reinforcing layer 3. Due to this
configuration, a rear surface of each of the leather panels 4, 4... configuring the
outer layer 5 faces the reinforcing layer 3 (the ball body 7). The leather panels
4, 4... are not bonded to the reinforcing layer 3.
[0019] As shown in Fig. 2, a leather panel 4 has a leather material 4c and a rear surface
member 4d pasted to the rear side of the leather material 4c. Artificial leather,
synthetic leather, or the like is used as the leather material 4c. The rear surface
member 4d of the leather panel 4 is configured with a soft, elastic material such
as an EVA foam material. The rear surface member 4d functions as a buffer member as
well. The leather panel 4 has a thickness of approximately 3 to 8 mm.
[0020] Each leather panel 4 has a main body 11 and an extending portion 12 that is thinner
than the main body 11 and extends from a side surface of the main body 11. The main
body 11 has a slightly smaller outer shape than the leather panel 4 (e.g., polygonal
shape, such as a pentagonal shape) but has an outer shape similar to that of the leather
panel 4. As shown in Fig. 2, the main body 11 has an even thickness throughout and
has a rectangular vertical cross section. The main body 11, therefore, has a front-side
surface 11 a configured by the leather material 4c, a rear-side surface 11b, opposite
to the front-side surface 11a, to which a reinforcing member 15 described hereinafter
is secured, and an outer end surface 11c connected to an outer circumferential portion
of the rear-side surface 11b.
[0021] The extending portion 12 is provided around the main body 11. The extending portion
12 has a front-side surface 12a connected to the front-side surface 11a of the main
body 11, an inner side surface 12b connected to the outer end surface 11c of the main
body 11, and a leading end surface 12c configuring an outer circumferential surface
of the extending portion 12. The extending portion 12 protrudes laterally (toward
the outer end surface) from the front side of the outer end surface 11 c of the main
body 11 and extends toward the rear side. In other words, the extending portion 12
is bent to the rear side.
[0022] The length by which the extending portion 12 extends from the main body 11 is approximately
equal to the thickness of the main body 11. The leading end surface 12c of the extending
portion 12 faces the ball body 7 at a position substantially flush with a rear-side
surface 11b of the main body 11. Therefore, the extending portion 12 abuts with the
ball body 7, preventing a peripheral portion of the main body 11 from lifting from
the ball body 7 and an outer circumferential portion of the leather panel 4 from bulging.
[0023] The outer end surface 11c of the main body 11 is configured in such a manner that
the back (rear-side portion) of the area where the extending portion 12 is formed
(front-side portion) remains in the form of an end surface. The inner side surface
12b of the extending portion 12 faces the rear-side portion of the outer end surface
11 c of the main body 11. The front-side surface 12a of the extending portion 12 is
formed with the leather material 4c.
[0024] The leather material 4c extends from the front-side surface 11 a of the main body
11 through the front-side surface 12a of the extending portion 12. That is, the leather
material 4c is provided from a front-side surface through an outer end surface of
the leather panel 4. Therefore, an outer circumferential portion of the leather material
4c is curved to the rear side.
[0025] The rear surface member 4d is provided on the inside so as to be surrounded with
the leather material 4c, and configures a range extending through the main body 11
to the extending portion 12 in the leather panel 4. In other words, the main body
11 has the leather material 4c and the rear surface member 4d, and the extending portion
12, too, has the leather material 4c and the rear surface member 4d.
[0026] The soccer ball according to the present embodiment is a so-called machine sewing
ball in which adjacent leather panels 4 are stitched together with a stitching thread
13.
[0027] The soccer ball according to the present embodiment is provided with the reinforcing
member 15 for reinforcing the parts stitched with the stitching thread 13.
[0028] The reinforcing member 15 is configured with one or more fabrics. The reinforcing
member 15 is configured with, for example, cotton, a mixed fabric of cotton and polyester,
a nylon fabric, or a polyester fabric. The tensile strength of the reinforcing member
15 is preferably 0.08 to 2.5 kgf/inch (0.31 to 9.6 N/cm) in both the vertical direction
and the horizontal direction.
[0029] The area density of the reinforcing member 15 (weight per unit area) is preferably
25 to 200 g/m
2. Every ball has its optimum weight range for adequately realizing the desired performance
when used in ball games. For instance, as to the soccer balls used in the international
games, the weight of a size 5 ball is extremely narrow, falling in the range of 420
to 445 g, as regulated by FIFA. This means nothing but the fact that a small weight
difference of ±10 g has significant impact on the ball games. In order to make the
balls of this size, normally a weight of 80 g to 100 g is used for a bladder, a weight
of 100 g to 120 g for a reinforcing layer, and hence the remaining weight of 200 to
240 g for the leather panels 4, 4... The weight of the leather materials 4c, 4c...
of the leather panels 4, 4... needs to be approximately 120 to 150 g. In the leather
panels 4, 4..., therefore, the remaining weight that can be applied to the members
other than the leather materials 4c, 4c... is 50 to 120 g. Because the weight of the
stitching thread 13 used in the present embodiment needs to be 10 g, the weight of
the other members of the leather panels 4, 4.., which are the rear surface members
4d, 4d..., the reinforcing members 15, 15... and an adhesive 17 is 40 to 110 g. Because
the rear surface members 4d, 4d... are used as buffer materials for absorbing impacts,
it is preferred that the rear surface members 4d, 4d... provide as much weight as
possible and thus weigh 35 to 70 g. Therefore, the weight of the reinforcing members
15, 15... is 5 to 40 g. It is not easy to accomplish objectives under such weight
regulations. The weight 5 to 40 g corresponds to the weight of a single ball; thus,
when configuring a reinforcing member 15 with a woven fabric, the area density of
the reinforcing member 15 becomes 25 to 200 g/m
2. Consequently, the weights of the materials that can be used for the reinforcing
member 15 need to fall within the foregoing range. If the materials for the reinforcing
member 15 weigh 200 g/m
2 or more, the panels become heavy, bringing about the need to reduce the weights of
the other members, and resulting in inability to keep sufficient quality of the ball.
[0030] The reinforcing member 15 is provided on the rear side of the rear surface member
4d. Specifically, the reinforcing member 15 has, integrally, a first section 15a secured
to the inner side surface 12b of the rear surface member 4d in the extending portion
12, a second section 15b secured to the outer end surface 11c of the rear surface
member 4d in the main body 11, and a third section 15c secured to the rear-side surface
11b of the rear surface member 4d in the main body 11.
[0031] The first section 15a is configured by an outer circumferential portion of the reinforcing
member 15 and disposed along the inner side surface 12b of the extending portion 12.
An outer end surface of the first section 15a is disposed flush with the leading end
surface 12c of the extending portion 12 and faces the ball body 7. The reinforcement
effect of the stitched portion between the extending portions 12 is achieved mainly
by the first section 15a. In other words, without the first section 15a, the stitches
on the rear surface member 4d made of a soft material tear easily, and cause stitch-skipping.
Consequently, the strength for withstanding use of the ball cannot be achieved.
[0032] The second section 15b is connected to the first section 15a by folding back from
the first section 15a, and is disposed along the outer end surface 11c of the main
body 11. Because the second section 15b is curved in such a manner as to fold back
from the first section 15a, a groove is formed on the rear surface of the leather
panel 4. This groove extends along the outer circumference of the leather panel 4
and is connected in the form of a ring.
[0033] The third section 15c is provided over the entire rear surface of the rear surface
member 4d in the main body 11. The third section 15c is in contact with the reinforcing
layer 3 in the ball body 7. However, the reinforcing member 15 is not bonded to the
reinforcing layer 3 with adhesive but is present independently from the reinforcing
layer 3.
[0034] Because the reinforcing member 15 is provided over the entire leather panel 4, the
reinforcing member 15 functions to reinforcing the entire ball along with the reinforcing
layer 3. In other words, since the reinforcing member 15 is configured to have integrally
the first section 15a, the second section 15b, and the third section 15c, the reinforcing
member 15 not only functions to reinforce the stitched portion between the extending
portions 12 but also functions to reinforce the entire ball. Because the reinforcing
member 15 is present independently from the reinforcing layer 3 of the ball body 7,
a member that is thinner than that of a conventional machine-sewn ball can be employed
as the reinforcing layer 3.
[0035] Note that the reinforcing member 15 may be configured without the third section 15c
or may be configured without the second section 15b and third section 15c. According
to such configurations, the weight of the entire ball can be reduced more than when
the reinforcing member 15 has the first section 15a, the second section 15b, and the
third section 15c.
[0036] In the configuration in which the reinforcing member 15 has the first section 15a
and the second section 15b but does not have the third section 15c, the rear-side
surface 11b of the main body 11 faces the ball body 7 (the reinforcing layer 3), as
shown in Fig. 3. In this case, the reinforcing member 15 that is shaped into a tape
and has a width corresponding to the width of the inner side surface 12b of the extending
portion 12 and the width of the outer end surface 11c of the main body 11 is used.
[0037] The adjacent leather panels 4, 4 are stitched together with the stitching thread
13. In other words, the leather material 4c, the rear surface member 4d and the reinforcing
member 15 of one of the leather panels 4 are stitched to the leather material 4c,
the rear surface member 4d and the reinforcing member 15 of the adjacent leather panel
4, with the stitching thread 13.
[0038] The yarn count of the stitching thread 13 is preferably 15 to 40 and more preferably
20 to 30.
[0039] The adjacent leather panels 4, 4 are bonded to each other with the adhesive 17. The
groove between the outer end surfaces of the leather panels 4 is filled with the adhesive
17, forming a V-shaped groove between the leather panels 4, 4 on the front side of
the adhesive 17 (the upper side of Fig. 2). Note that the adhesive 17 is applied not
only to the groove between the outer end surfaces of the leather panels 4 but also
to the leading end surface 12c of the extending portion 12 of each panel 4.
[0040] The adhesive 17 covers the stitched portion including the stitching holes formed
by the stitching thread 13. In other words, the stitching thread 13 penetrates a layer
configured by the adhesive 17. For this reason, the stitching thread 13 cannot be
seen from the outside. Due to the presence of the adhesive 17 around the stitching
holes, the stitching holes on the leather material 4c are closed with the adhesive
17, preventing water from seeping into the ball.
[0041] The adhesive 17 is made of a heat active type adhesive 17. Specifically, the adhesive
17 applied to each of the extending portions 12 of the leather panels 4 is dried and
solidified at room temperature. The adhesive that is solidified on each of the extending
portions 12 melts and becomes fused by being heated at, for example, approximately
45 to 65°C. Thereafter, the adhesive 17 on the extending portions 12 is bonded together
and eventually solidified. The melted adhesive 17 flows into the stitching holes to
close the stitching holes, further reinforcing the effect of preventing absorption
of water into the ball.
[0042] The reinforcing member 15 is provided in the rear surface member 4d, as shown in
Fig. 4. In this case, the rear surface member 4d consists of a front-side portion
4f located on the leather material 4c side of the reinforcing member 15 and a rear-side
portion 4g located on the opposite side to the leather material 4c with respect to
the reinforcing member 15. Specifically, the reinforcing member 15 is sandwiched between
the front-side portion 4f and the rear-side portion 4g. The presence of the front-side
portion 4f on the leather material 4c side of the reinforcing member 15 can prevent
deterioration of the ball texture.
[0043] In this case as well, the reinforcing member 15 is provided over the range extending
through the main body 11 to the extending portion 12. The reinforcing member 15 has
the area disposed on the inside of the extending portion 12 and the area disposed
on the inside of the main body 11, and has an outer circumferential area curved, as
with the leather material 4c.
[0044] A method for manufacturing the soccer ball according to the present embodiment is
now described.
[0045] First, a step of forming the leather panel 4 is described. This leather panel formation
step entails forming a member for leather panel 19 having a shape corresponding to
the shape of the leather panel 4 and forming the leather panel 4 from the member for
leather panel 19. This step includes a pasting step, a cutting step, and an extending
portion formation step.
[0046] In the pasting step, the rear surface member 4d and the reinforcing member 15 are
attached to the rear side of the leather material 4c as shown in Fig. 5. Natural latex
can be used as an adhesive. The leather material 4c and the rear surface member 4d
may be secured to each other with the adhesive. The rear surface member 4d and the
reinforcing member 15 may also be secured to each other by the adhesive. At this stage,
the leather material 4c, the rear surface member 4d, and the reinforcing member 15
are not yet cut, and therefore are not in the shape corresponding to the shape of
the leather panel 4. Fig. 5 shows a case of the soccer ball shown in Fig. 2. The rear
surface member 4d is attached to the rear side of the leather material 4c and the
reinforcing member 15 is attached to the rear side of the rear surface member 4d.
In the soccer ball shown in Fig. 4, the reinforcing member 15 is attached between
the front-side portion 4f and rear-side portion 4g of the rear surface member 4d.
All the rest are the same.
[0047] As shown in Fig. 6, in the cutting step, the leather material 4c, the rear surface
member 4d, and the reinforcing member 15 are cut altogether into the shape corresponding
to the shape of the leather panel, to obtain the member for leather panel 19. In order
to cut these members, these members may be cut by cutting die 18 or cut out using
a cutter, not shown.
[0048] In the extending portion formation step, the leather panel 4 in which the main body
11 and the extending portion 12 are formed is obtained by denting an outer circumferential
portion of the member for leather panel 19. In the extending portion formation step,
a depressed portion forming apparatus 20 is used, as shown in Fig. 7. This depressed
portion forming apparatus 20 has a first die 21, a second die 22, and a temperature-raising
portion 24 for raising the temperature of the outer circumferential portion of the
member for leather panel 19.
[0049] The first die 21 has a flat portion 21 a for pressing a front-side surface of the
member for leather panel 19. The second die 22, on the other hand, is provided with
an annular projection 22a for forming a depressed portion 26 on the outer circumferential
portion of the member for leather panel 19. The vertical cross section of this annular
projection 22a is formed into, for example, a rectangle, and a depressed portion 22b
surrounded by the annular projection 22a has the size and shape (similar shape) corresponding
to the main body 11 of the leather panel 4.
[0050] The temperature-raising portion 24 is configured with a high frequency generator
or an ultrasonic generator. In case of a high frequency generator, the temperature-raising
portion 24 is configured to apply a high-frequency voltage (e.g., 10 kHz, voltage
of several thousand volts) between the first die 21 and the second die 22 taken as
electrodes. Then, a peripheral portion of the member for leather panel 19 is compressed
with the first die 21 and the annular projection 22a of the second die 22. In so doing,
a member for leather panel 19 is set in such a manner that the leather material 4c
is located on the first die 21 side and the reinforcing member 15 on the annular projection
22a side. A high-frequency voltage can be applied between the electrodes until the
temperature becomes equal to or higher than a temperature at which the rear surface
member 4d melts at the position corresponding to the annular projection 22a.
[0051] Once the temperature of the outer circumferential portion of the member for leather
panel 19 increases, an outer circumferential portion of the rear surface member 4d
that corresponds to the area between the annular projection 22a and the flat portion
21a melts and becomes compressed. As a result, the depressed portion 26 that is dented
on the reinforcing member 15 side is formed in the outer circumferential portion of
the rear surface member 4d. At this moment, the reinforcing member 15 becomes deformed
without being melted, in response to the melting and compression of the rear surface
member 4d (see Fig. 8). As a result, the leather panel 4 in which the main body 11
and the extending portion 12 are formed can be obtained. The depressed portion 26
is formed into a thickness that allows the extending portion 12 to be folded. At this
moment, however, the extending portion 12 is not yet folded and extends laterally
and straight from the main body 11 into the shape of a flange.
[0052] When manufacturing the soccer ball shown in Fig. 4, the temperature-raising portion
24 is not limited to the configuration of raising the temperature of the peripheral
portion of the member for leather panel 19 at a high-frequency voltage. The temperature-raising
portion 24 may be configured with, for example, a heater, not shown, which is embedded
in the second die 22. The member for leather panel 19 is heated by increasing the
temperature of the annular projection 22a with the heat of the heater.
[0053] Subsequently, the adhesive 17 is applied to an outer surface of the extending portion
12 in the leather panel 4 (the application step). As show in Fig. 9, in the application
step, the adhesive 17 is applied to the area that eventually forms the outer end surface
of the leather panel 4 when the extending portion 12 is bent. The adhesive 17 is made
of a heat active type adhesive. The adhesive 17 is dry and solid but melts when heated.
[0054] Next, the outer surfaces of two leather panels 4 are brought into contact with each
other, as shown in Fig. 10 (the joining step). In so doing, because the adhesive 17
is already applied to the outer circumferential portions of the outer surfaces of
the leather panels, the areas applied with the adhesive 17 face each other.
[0055] Thereafter, the extending portions 12 of the leather panels 4, the outer surfaces
of which have been joined to each other, are stitched together with the stitching
thread 13 (the stitching step). In the stitching step, a sewing machine needle 28
with the stitching thread 13 is passed through the reinforcing member 15, the rear
surface members 4d, and the leather materials 4c of the both leather panels 4, to
stitch these members together. Then, the joining step and the stitching step are repeated
to form a spherical shell body 30 (see Fig. 11). In so doing, sides that are not stitched
are ensured to create an opening into which the ball body 7 is inserted.
[0056] In this spherical shell body 30, the reinforcing members 15 are located on the front
side and the extending portions 12 are folded to the front side, as shown in Fig.
12. Thus, the spherical shell body 30 is turned over using the abovementioned opening.
The ball body 7 is inserted into the spherical shell body 30 and the opening is stitched
and closed, forming a ball (the insertion step).
[0057] Next, as shown in Fig. 13, the ball is inserted into a mold 33, high-pressure air
(6 to 8 kg/cm
2) is injected into the bladder 2 with the mold 33 closed, and the mold 33 is pressurized
and heated. As a result, the adhesive 17 on each extending portion 12 melts once and
becomes bonded (fused) and thereafter solidified (the fusing and solidification step).
Specifically, the mold 33 is heated to a temperature at which the adhesive 17 shows
activity, and thereafter the ball is cooled, thereby bonding the adjacent leather
panels 4 to each other. As a result, the soccer ball is completed.
[0058] According to the present embodiment described above, the areas of the extending portions
12 of the adjacent leather panels 4 that are stitched with the stitching thread 13
are reinforced by the reinforcing member 15. Therefore, seam tear and stitch-skipping
are not likely to occur between the extending portions 12 of the leather panels 4.
Moreover, the extending portions 12 of the adjacent leather panels 4 are bonded to
each other with the adhesive 17. For this reason, it is unlikely that the stitching
thread 13 be exposed when the soccer ball is in use. Even when force acts on the ball
to split the adjacent leather panels 4, 4 apart, tension acting on the stitching thread
13 is reduced because the tight adhesion between the extending portions 12 is kept
by the adhesive 17. Therefore, the stitching thread 13 is not torn easily. In addition,
the space between the panels 4 is covered with the adhesive 17 and the stitching holes
are securely closed with the melted adhesive 17, preventing water from seeping through
the stitching holes. Furthermore, because the extending portion 12 is made thinner
than the main body 11, the presence of the extending portion 12 prevents the outer
circumferential portion of the leather panel 4 from bulging. In other words, in a
conventional stitched ball in which the outer circumferential portion having the same
thickness as the main body is folded inward, the outer circumferential portion of
each leather panel comes into contact with the ball body and the peripheral portion
of the main body lifts from the ball body to cause the outer circumferential portion
of each leather panel to bulge toward the front side. In the soccer ball according
to the present embodiment, on the other hand, such a phenomenon does not occur because
the extending portion 12 is made thinner than the main body 11.
[0059] Next is described the effect of reinforcing the stitched portion between the leather
panels 4, the effect being accomplished not only by the configuration in which the
leather panels 4 are stitched together with the stitching thread 13 and the end surfaces
of the leather panels 4 are bonded to each other by the adhesive 17, but also by providing
the reinforcing member 15 on the rear side of each leather panel 4.
[0060] For the purpose of enhancing the adhesive effect (adhesive strength) of the adhesive
17, it is essential to press (apply pressure to) the leather panels 4 to be bonded.
The configuration in which the end surfaces of the panels are simply bonded to each
other, unfortunately, cannot generate force that presses the end surfaces against
each other. Thus, application of pressure to the bonded surfaces of the leather panels
4 is realized by sewing the end surfaces of the both panels 4 together, with the reinforcing
members 15 interposed therein. Compared to not sewing the end surfaces, sewing the
end surfaces can increase the adhesive strength.
[0061] This aspect is now described in more detail. Since the rear surface member 4d is
a buffer material, the entire stitching thread 13 is buried in the rear surface member
4d when the reinforcing member 15 is not provided. Therefore, in spite of the configuration
of stitching the leather panels 4 together with the stitching thread 13, if the reinforcing
member 15 is not provided, the force of pressurizing the bonded surfaces of the leather
panels 4 becomes weak. On the other hand, if the reinforcing member 15 is provided,
the stitching thread 13 acts between stitching holes to press the rear surface member
4d via the reinforcing member 15, and thus acts to press the bonded surfaces of the
leather panels 4 without having the sewing force absorbed by the rear surface member
4d. Specifically, the tensile force of the stitching thread 13 only acts on the part
where the stitching thread 13 is in contact with the leather panels 4, if the leather
panels 4 are simply stitched together but are not bonded to each other. Consequently,
the leather panels 4 cannot be pressed in a wide area thereof. Moreover, without the
reinforcing member 15, the bonded surfaces of the leather panels 4 cannot be pressed
effectively by the tension of the stitching thread 13. Also, when a heat active type
adhesive is used, the adhesive that is applied to and melted on both of the end surfaces
of the leather panels 4 becomes mixed up and pressurized by the pressure obtained
by sewing the end surfaces. Consequently, the adhesive strength of the heat active
type adhesive increases. By stitching and bonding the leather panels 4 to each other
and incorporating the reinforcing member 15, the durability of the panels 4 (the outer
layer 5) can be improved due to these synergetic effects.
[0062] In the present embodiment, the reinforcing member 15 is provided over the range extending
from the extending portion 12 through the main body 11. The reinforcing member 15
not only reinforces the stitched portion between the extending portions 12 but also
provides the reinforcement effect of the leather panels 4. The use of the reinforcing
member 15 of the size equivalent to the range between the extending portion 12 and
the main body 11 can prevent complexification of the process of attaching the reinforcing
member 15 to the member for leather panel 19. In other words, the process of attaching
the reinforcing member can be made simpler than that of attaching the reinforcing
member 15 to the main body 11 and the extending portion 12 separately. Positional
displacement of the reinforcing member 15 can be prevented as well.
[0063] In the present embodiment, the reinforcing member 15 is provided over a range including
the rear-side surface 11b of the main body 11 that faces the ball body 7, the rear-side
portion of the outer end surface 11c of the main body 11, and the inner side surface
12b of the extending portion 12 that faces the outer end surface 11c of the main body
11. Specifically, the reinforcing member 15 is provided on the inner side surface
12b of the extending portion 12 that faces the outer end surface 11c of the main body
11. For this reason, seam tear and stitch-skipping are not likely to occur in the
extending portion 12 of the leather panel 4. The presence of the rear surface member
4d between the reinforcing member 15 and the leather material 4c can provide a feature
of a ball for ball games, such as being soft to the touch. Since the reinforcing member
15 is also provided on the rear-side surface 11b of the main body 11 that faces the
ball body 7, the reinforcing member 15 functions to reinforce the ball.
[0064] Even in the configuration in which the reinforcing member 15 is provided on the inside
of the rear surface member 4d as shown in Fig. 4, seam tear and stitch-skipping are
not likely to occur. Furthermore, by heating the rear surface member 4d or increasing
the temperature by applying high-frequency voltage to the rear surface member 4d,
the depressed portion 26 can be formed in the peripheral portion of the rear surface
member 4d.
[0065] In the present embodiment, the adhesive 17 is a heat active type adhesive. The adhesive
17 therefore can be applied to the outer circumferential portion of the outer surface
of each leather panel 4 prior to stitching the extending portions 12 of the leather
panels together. Specifically, after the adhesive 17 that is applied to the outer
circumferential portion of the outer surface of each leather panel 4 is dried, the
extending portions 12 of the leather panels 4 can be stitched together. Therefore,
compared to when injecting the adhesive between the leather panels 4, 4 after stitching
the leather panels 4 together, the time it takes to create the outer layer 5 can be
reduced more. The adhesive 17 is heated, with the adjacent leather panels 4, 4 being
stitched together with the stitching thread 13, completing adhesion of the leather
panels 4, 4. Because the adjacent leather panels 4, 4 are bonded to each other while
being pressed by the stitching thread 13, the adhesive molecules applied to the panels
4, 4 melt (mutual melting) and become bonded to each other. Consequently, high adhesive
strength can be obtained. When injecting the adhesive between the leather panels 4,
4 after stitching the leather panels 4, 4 together, mutual melting does not take place
and the adhesive strength is weak due to the absence of the pressure force.
[0066] In the manufacturing method according to the present embodiment, the outer surfaces
of the extending portions 12 to which the adhesive 17 is applied are joined to each
other and the extending portions 12 are stitched together with the stitching thread
13. This procedure reduces the manufacturing time more compared to when injecting
the adhesive between the adjacent leather panels 4, 4 after stitching the leather
panels 4, 4 together. Forming the reinforcing member 15 in each of the extending portions
12 to be stitched together prevents the occurrence of seam tear and stitch-skipping
during the stitching step.
[0067] In the manufacturing method according to the present embodiment, the reinforcing
member 15 is attached to the rear surface member 4d, and thereafter the leather material
4c, the rear surface member 4d, and the reinforcing member 15 are cut altogether into
a shape corresponding to the shape of the leather panels. Therefore, compared to when
attaching to the rear surface member 4d the reinforcing member 15 that is cut into
the shape of the leather panels, the burden involved in the process of attaching the
reinforcing member 15 can be alleviated more. Specifically, because the reinforcing
member 15 is not yet cut at the time of attaching the reinforcing member 15, precise
positioning of the reinforcing member 15 is not necessary. This reduces the burden
involved in the attaching process. Moreover, positional displacement of the reinforcing
member 15 can be prevented. Because the extending portion 12 is formed after the rear
surface member 4d is attached to the rear side of the leather material 4c and cut,
positional displacement of the rear surface member 4d itself can be prevented as well.
In other words, in a case where the extending portion is formed by cutting the leather
material and then attaching the cut rear surface member thereto, there is a possibility
that positional displacement of the rear surface member might occur, causing differences
in length of the extending portion. This leads to a fluctuation in the shape of the
leather panels when the extending portion is bent, deteriorating the aesthetic aspect
of the ball for ball games. On the other hand, in a case where the reinforcing member
15 is attached to the rear surface member 4d and thereafter the leather material 4c,
the rear surface member 4d, and the reinforcing member 15 are cut altogether, positional
displacement of the rear surface member 4d does not occur, preventing deterioration
of the aesthetic aspect of the ball for ball games.
[0068] In the manufacturing method according to the present embodiment, the extending portion
12 extending from the main body 11 is formed by denting the outer circumferential
portion of the rear surface member 4d to which the reinforcing member 15 is attached.
Therefore, the extending portion 12 reinforced with the reinforcing member 15 can
be formed easily. In the configuration in which the reinforcing member is attached
to the rear surface member after denting the outer circumferential portion of the
rear surface member, the process of attaching the reinforcing member is complicated,
possibly causing positional displacement of the location for attaching the reinforcing
member. However, in attaching the reinforcing member 15 and then denting the outer
circumferential portion of the rear surface member 4d that is cut into the shape corresponding
to the shape of the leather panels, the burden involved in the work of attaching the
reinforcing member 15 can be alleviated, preventing positional displacement of the
reinforcing member 15.
[0069] In the manufacturing method according to the present embodiment, denting the rear
surface member 4d at once can realize easy formation of the extending portion 12.
Therefore, the extending portion 12 of uniform width can be realized. In addition,
the panels can be sewn together with reference to the boundary between the extending
portion 12 and the main body 11 (depressed portion boundary). Consequently, the extending
portion 12 that is folded after sewing provides uniform height, improving the aesthetic
aspect of the ball. In a conventional method, on the other hand, the absence of a
sewing guideline makes the distance from a panel end surface (margin) uneven and thus
creates an uneven folded margin after sewing, deteriorating the aesthetic aspect of
the ball.
[0070] In the manufacturing method according to the present embodiment, because the outer
circumferential portion of the rear surface member 4d to which the reinforcing member
15 has been attached is melted and then dented, the depressed portion can easily be
formed in the outer circumferential portion of the rear surface member 4d to which
the reinforcing member 15 is attached. Even when melting the rear surface member 4d,
the reinforcing member 15 does not come off the rear surface member 4d. Since the
area of the reinforcing member 15 that is pressed by the annular projection 22a of
the second die 22 and the area of the same that is not pressed by the annular projection
22a are clearly bounded, leather panels 4, 4 can be sewn together with reference to
this boundary. Specifically, the reinforcing member 15 is made of a woven fabric wherein
a surface has irregularities formed by the warp and weft and, in some cases, wrinkles.
Although the area of the reinforcing member 15 that is pressed by the annular projection
22a can become free of the surface irregularities and become flat, the other areas
still have the surface irregularities. The presence/absence of the irregularities
on the surface is a cause of visual differences on the surface. As a result, an annular
area that has a smooth surface and a constant width is formed in the outer circumferential
portion of the reinforcing member 15. Therefore, the panels can be sewn together along
the boundary between the area with a smooth surface and the area without, whereby
the height of the extending portion 12 is likely to be constant when the extending
portion 12 is folded. In the conventional technique shown in Fig. 14, because the
folding portion 59 is made of a sponge, the folding portion 59 and the other areas
have equally smooth surfaces in spite of the difference in level on these areas. For
this reason, the folding portion 59 and the other areas show less visual differences,
making boundaries less visible at the time of sewing.
[0071] In the manufacturing method according to the present embodiment, the adhesive 17
is dry in the stitching step. Therefore, the adhesive 17 can be prevented from adhering
to an unintended area during the process of stitching the extending portions 12. In
addition, because the ball body 7 is inserted into the spherical shell body 30 and
thereafter the adhesive 17 is melted to completely bond the extending portions 12
to each other, the space between the leather panels 4, 4 can be closed neatly. At
this moment, the area between the extending portions 12 that is stitched with the
stitching thread 13 can be completely covered by the adhesive 17. The adhesive 17
is heated, with the adjacent leather panels 4, 4 being stitched together with the
stitching thread 13, completing adhesion of the adjacent leather panels 4, 4. As a
result, the adjacent leather panels 4, 4 are bonded to each other while being pressed
by the stitching thread 13, achieving high adhesive force.
[0072] It should be noted that the present invention is not limited to the foregoing embodiment,
and various changes and improvements can be made without departing from the gist of
the present invention. For example, although the foregoing embodiment has described
an example in which the present invention is applied to a soccer ball, the present
invention can be applied to other types of balls for various ball games, such as valley
balls, handballs, basketballs, rugby balls, American footballs, netballs, futsal balls,
beach soccer balls, Australian footballs, rugby league footballs, rugby union footballs,
and touch balls.
[0073] According to the foregoing embodiment, a heat active type adhesive is used as the
adhesive 17, but other types of adhesives may be applicable.
[0074] The foregoing embodiment is summarized below.
- (1) The ball for ball games according to the foregoing embodiment has a ball body
and a spherical shell-shaped outer layer having a plurality of leather panels and
disposed on the outside of the ball body. The plurality of leather panels each have
a main body and an extending portion that is thinner than the main body and extends
from a front-side portion of an outer end surface of the main body to configure an
outer end surface of the leather panel. The extending portions of adjacent leather
panels are bonded to each other with an adhesive and stitched together with a stitching
thread. The extending portion is provided with a reinforcing member for reinforcing
an area thereof stitched with the stitching thread.
In the ball for ball games according to the foregoing embodiment, the areas of the
extending portions of the leather panels that are stitched together by the stitching
thread are reinforced by the reinforcing member. Therefore, seam tear and stitch-skipping
are not likely to occur in the extending portions of the leather panels. Moreover,
the extending portions of the adjacent leather panels are bonded to each other with
the adhesive. Therefore, it is unlikely that the stitching thread be exposed when
the ball for ball games is in use. Even when force acts on the ball to split the adjacent
leather panels apart, the tension acting on the stitching thread can be reduced because
the tight adhesion between the extending portions is kept by the adhesive. Consequently,
the stitching thread is not torn easily. In addition, the space between the leather
panels and the stitching holes are closed securely with the adhesive, preventing water
from seeping through the space between the leather panels or the stitching holes.
Because the extending portion is made thinner than the main body, the presence of
the extending portion or margin prevents the outer circumferential portion of the
leather panel from bulging. In other words, in the conventional stitched ball in which
the outer circumferential portion having the same thickness as the main body is folded
inward, the outer circumferential portion or margin of each leather panel comes into
contact with the ball body to lift the peripheral portion of the main body off the
ball body, resulting in bulging of the outer circumferential portion or margin of
the leather panel to the front side. In the ball for ball games according to the present
embodiment, on the other hand, such a phenomenon does not occur because the extending
portion is made thinner than the main body.
- (2) The main body and the extending portion may each have a leather material and a
rear surface member secured to a rear surface of the leather material. In this case,
the reinforcing member may be provided over a range including a rear-side portion
of the outer end surface of the main body and an inner side surface of the extending
portion that faces the rear-side portion of the outer end surface of the main body.
According to this aspect, the extending portions that each has the leather material
and the rear surface member are stitched together with the stitching thread. Also,
the reinforcing member is provided on the inner side surface of the extending portion
that faces the outer end surface of the main body. Therefore, seam tear and stitch-skipping
are not likely to occur in the extending portion of each leather panel. The presence
of the rear surface member between the reinforcing member and the leather material
can provide a feature of a ball for ball games, such as being soft to the touch.
- (3) The reinforcing member may be provided over a range extending from the extending
portion through the main body.
According to this aspect, the reinforcing member not only reinforces the stitched
portions of the extending portions but also provides the reinforcement effect of the
leather panel. The use of the reinforcing member of the size equivalent to the range
between the extending portion and the main body can prevent complexification of the
process of providing the reinforcing member to the member for leather panel. In other
words, compared to when attaching each individual reinforcing member to the main body
and the extending portion, the process of attaching the reinforcing member can be
simplified. Positional displacement of the reinforcing member can be prevented as
well.
- (4) The main body and the extending portion may each have a leather material and a
rear surface member secured to a rear surface of the leather material. In this case,
the reinforcing member may be provided over a range including a rear-side surface
of the main body that faces the ball body, a rear-side portion of the outer end surface
of the main body, and an inner side surface of the extending portion that faces the
rear-side portion of the outer end surface of the main body.
According to this aspect, the extending portions that each has the leather material
and the rear surface member are stitched together with the stitching thread. Also,
the reinforcing member is provided on the inner side surface of the extending portion
that faces the outer end surface of the main body. Therefore, seam tear and stitch-skipping
are not likely to occur in the extending portion of each leather panel. The presence
of the rear surface member between the reinforcing member and the leather material
can provide a feature of a ball for ball games, such as being soft to the touch. The
reinforcing member is also provided on the rear surface of the main body that faces
the ball body, to reinforce the ball.
- (5) The main body and the extending portion may each have a leather material and a
rear surface member secured to a rear surface of the leather material. In this case,
the reinforcing member may be provided in the rear surface member of each of the main
body and the extending portion.
According to this aspect, the extending portions that each has the leather material
and the rear surface member are stitched together with the stitching thread. Because
the reinforcing member is provided between the leather material and the rear surface
member of each of the extending portions of the leather panels, seam tear and stitch-skipping
are not likely to occur. Moreover, a depressed portion can be formed in the peripheral
portion of the rear surface member by heating the rear surface member or increasing
the temperature by applying a high-frequency voltage or ultrasonic wave to the rear
surface member.
- (6) The adhesive may be a heat active type adhesive.
According to this aspect, the adhesive can be applied to the outer circumferential
portion of the outer surface of each leather panel prior to stitching the extending
portions of the leather panels together. In other words, the extending portions of
the leather panels can be stitched together after the adhesive applied to the outer
circumferential portion of the outer surface of each leather panel is dried. Therefore,
compared to when injecting the adhesive between the leather panels after stitching
the leather panels together, the time it takes to create the outer layer can be reduced
more. The adhesive is heated, with the adjacent leather panels being stitched together
with the stitching thread, completing adhesion of the leather panels. Because the
adjacent leather panels are bonded to each other while being pressed by the stitching
thread, high adhesive strength can be obtained.
- (7) It is preferred that the reinforcing member have an area density of 25 to 200
(25 or greater and 200 or less) g/m2. According to this aspect, keeping sufficient quality of the ball for ball games
while preventing an excessive increase in the weight of the ball can be accomplished.
- (8) The foregoing embodiment is a method for manufacturing a ball for ball games that
has a ball body and a spherical shell-shaped outer layer having a plurality of leather
panels and disposed on the outside of the ball body, the method having: a leather
panel formation step of obtaining each of the leather panels by forming, in a member
for leather panel, a main body and an extending portion reinforced with a reinforcing
member; an application step of applying an adhesive to an outer surface of each of
the extending portions; a joining step of bringing the outer surfaces of the extending
portions of two leather panels to which the adhesive is applied into contact with
each other; a stitching step of stitching together, with a stitching thread, the extending
portions of the leather panels, the outer surfaces of which have come into contact
with each other; and an insertion step of inserting the ball body into a spherical
shell body that is obtained by repeating the joining step and the stitching step,
to obtain a ball.
According to this manufacturing method, the outer surfaces of the extending portions
to which the adhesive is applied are brought into contact with each other, and then
the extending portions are stitched together with the stitching thread. Therefore,
compared to when injecting the adhesive between adjacent leather panels after stitching
the leather panels together, the manufacturing time can be reduced more. In addition,
because the reinforcing member is provided in each of the extending portions to be
stitched together, seam tear and stitch-skipping are not likely to occur during the
stitching step.
- (9) The leather panel formation step may include a step of attaching a rear surface
member and the reinforcing member to a rear side of a leather material, and a step
of cutting the leather material, the rear surface member, and the reinforcing member
altogether into a shape corresponding to the shape of the leather panels.
According to this aspect, the reinforcing member is attached to the rear surface member,
and thereafter the leather material, the rear surface member, and the reinforcing
member are cut altogether into a shape corresponding to the shape of the leather panels.
Therefore, compared to when attaching to the rear surface member the reinforcing member
that is cut into the shape of the leather panels, the burden involved in the process
of attaching the reinforcing member can be alleviated more. Specifically, because
the reinforcing member is not yet cut at the time of attaching the reinforcing member,
precise positioning of the reinforcing member is not necessary. This reduces the burden
involved in the attaching process. Moreover, positional displacement of the reinforcing
member can be prevented. Because the rear surface member is attached to the rear side
of the leather material and then cut, positional displacement of the rear surface
member itself can be prevented as well. In other words, in a case where the extending
portion is formed by cutting the leather material and then attaching the cut rear
surface member thereto, there is a possibility that positional displacement of the
rear surface member might occur, causing difference in length of the extending portion.
This leads to a fluctuation in the shape of the leather panels when the extending
portion is bent, deteriorating the aesthetic aspect of the ball for ball games. On
the other hand, in a case where the reinforcing member is attached to the rear surface
member and thereafter the leather material, the rear surface member and the reinforcing
member are cut altogether, positional displacement of the rear surface member does
not occur, preventing deterioration of the aesthetic aspect of the ball for ball games.
- (10) The leather panel formation step may further include an extending portion formation
step of forming the main body and the extending portion in each of the leather panels
by denting an outer circumferential portion of the rear surface member that is cut
into the shape of the leather panels.
According to this aspect, the extending portion extending from the main body is formed
by denting the outer circumferential portion of the rear surface member to which the
reinforcing member has been attached. Accordingly, the extending portion that is reinforced
with the rear surface member can be formed easily. In addition, the rear surface member
is press-fitted between the fibers of the reinforcing member in the course of denting
the rear surface member, resulting in enhancement of the securing strength between
the rear surface member and the reinforcing member and the material strength of the
reinforcing member itself. This is advantageous in terms of being able to enhance
the reinforcement effect of the reinforcing member without causing an excessive increase
in the weight of the ball.
The process of attaching the reinforcing member becomes complicated in the configuration
in which the reinforcing member is attached to the rear surface member after denting
the outer circumferential portion of the rear surface member, and in some cases the
position for pasting the reinforcing member can be displaced. In the present embodiment,
on the other hand, not only is it possible to alleviate the burden involved in the
process of attaching the reinforcing member, but also positional displacement of the
reinforcing member can be prevented, in the configuration of denting the outer circumferential
portion of the rear surface member that has the reinforcing member attached thereto
and is cut into a shape corresponding to the shape of the leather panels.
- (11) In the extending portion formation step, the outer circumferential portion of
the rear surface member to which the reinforcing member has been attached may be melted
and dented.
According to this aspect, a depressed portion can easily be formed on the outer circumferential
portion of the rear surface member to which the reinforcing member has been attached.
Even when melting the rear surface member, the reinforcing member does not come off
the rear surface member.
- (12) In the stitching step, the leather panels may be sewn together along a boundary
between an area of the reinforcing member that has a smooth outer circumferential
portion and an area on the inside thereof that has surface irregularities. According
to this aspect, the leather panels can be sewn together by taking advantage of the
visual difference between the area of the reinforcing member that has a smooth outer
circumferential portion and the area on the inside thereof that has surface irregularities.
- (13) In the application step, the adhesive made of a heat active type adhesive may
be applied, and the ball may be heated to melt the adhesive after the insertion step.
The adhesive is dry during the stitching step. Therefore, the adhesive can be prevented
from adhering to an unintended area during the process of stitching the extending
portions together. In addition, because the adhesive is melted to completely bond
the extending portions to each other after the insertion step, the space between the
leather panels can be closed neatly. At this moment, the sections of the extending
portions that are stitched with the stitching thread can be completely covered by
the adhesive. The adhesive is heated, with the adjacent leather panels being stitched
together with the stitching thread, completing adhesion of the leather panels. As
a result, the adjacent leather panels are bonded to each other while being pressed
by the stitching thread, achieving high adhesive force.
1. A ball for ball games, comprising:
a ball body; and
a spherical shell-shaped outer layer having a plurality of leather panels and disposed
on an outside of the ball body,
wherein the plurality of leather panels each have a main body and an extending portion
that is thinner than the main body and extends from a front-side portion of an outer
end surface of the main body to configure an outer end surface of the leather panel,
the extending portions of adjacent leather panels are bonded to each other with an
adhesive and stitched together with a stitching thread, and
the extending portion is provided with a reinforcing member for reinforcing an area
thereof stitched with the stitching thread.
2. The ball for ball games according to claim 1, wherein the main body and the extending
portion each have a leather material and a rear surface member secured to a rear surface
of the leather material, and
the reinforcing member is provided over a range including a rear-side portion of the
outer end surface of the main body and an inner side surface of the extending portion
that faces the rear-side portion of the outer end surface of the main body.
3. The ball for ball games according to claim 1, wherein the reinforcing member is provided
over a range extending from the extending portion through the main body.
4. The ball for ball games according to claim 3, wherein the main body and the extending
portion each have a leather material and a rear surface member secured to a rear surface
of the leather material, and
the reinforcing member is provided over a range including a rear-side surface of the
main body that faces the ball body, a rear-side portion of the outer end surface of
the main body, and an inner side surface of the extending portion that faces the rear-side
portion of the outer end surface of the main body.
5. The ball for ball games according to claim 2, wherein the main body and the extending
portion each have a leather material and a rear surface member secured to a rear surface
of the leather material, and
the reinforcing member is provided in the rear surface member of each of the main
body and the extending portion.
6. The ball for ball games according to any one of claims 1 to 5, wherein the adhesive
is a heat active type adhesive.
7. The ball for ball games according to any one of claims 1 to 6, wherein the reinforcing
member has an area density of 25 to 200 g/m2.
8. A method for manufacturing a ball for ball games that has a ball body and a spherical
shell-shaped outer layer having a plurality of leather panels and disposed on an outside
of the ball body, the method comprising:
a leather panel formation step of obtaining each of the leather panels by forming,
in a member for leather panel, a main body and an extending portion reinforced with
a reinforcing member;
an application step of applying an adhesive to an outer surface of each of the extending
portions;
a joining step of bringing the outer surfaces of the extending portions of two leather
panels to which the adhesive is applied into contact with each other;
a stitching step of stitching together, with a stitching thread, the extending portions
of the leather panels, the outer surfaces of which have come into contact with each
other; and
an insertion step of inserting the ball body into a spherical shell body that is obtained
by repeating the joining step and the stitching step, to obtain a ball.
9. The method for manufacturing a ball for ball games according to claim 8, wherein the
leather panel formation step includes:
a step of attaching a rear surface member and the reinforcing member to a rear side
of a leather material; and
a step of cutting the leather material, the rear surface member, and the reinforcing
member altogether into a shape corresponding to the shape of the leather panels.
10. The method for manufacturing a ball for ball games according to claim 8 or 9, wherein
the leather panel formation step further includes an extending portion formation step
of forming the main body and the extending portion in each of the leather panels by
denting an outer circumferential portion of the rear surface member that is cut into
the shape of the leather panels.
11. The method for manufacturing a ball for ball games according to claim 10, wherein
in the extending portion formation step, the outer circumferential portion of the
rear surface member to which the reinforcing member has been attached is melted and
dented.
12. The method for manufacturing a ball for ball games according to claim 10 or 11, wherein
in the stitching step, the leather panels are sewn together along a boundary between
an area of the reinforcing member that has a smooth outer circumferential portion
and an area on the inside thereof that has surface irregularities.
13. The method for manufacturing a ball for ball games according to any one of claims
8 to 12, wherein in the application step, the adhesive made of a heat active type
adhesive is applied, and
the ball is heated to melt the adhesive after the insertion step.